Manually set magnetic relay

ABSTRACT

A manually set magnetic relay is utilized to override an electrical interlock in a one-time operation. Once the relay has been utilized, it automatically disables itself and must be manually set again for another operation. The relay includes an electromagnetic coil which closes a set of load contacts that are connected in parallel with the electrical interlock. A secondary circuit for energizing the coil includes a pair of flexible conductors forming a switch which is latched open when the coil is de-energized. To close the switch and energize the coil, a manually actuated plunger engages one of the conductors and moves it from the latched position into contact with the other conductor of the switch. The plunger, during actuation, also holds the load contacts open to provide trip-free operation. A one-piece push button having flexible sidewalls is conveniently used to actuate the plunger.

United States Patent 1 Evans Feb.4, 1975 [73] Assignee: Texas Instruments Incorporated,

Dallas, Tex.

22 Filed: Dec. 5, 1973 21 Appl. No.: 421,902

[52] US. Cl 335/186, 123/179, 180/82 C,

335/164, 340/52 E [51] Int. Cl. H0lh 45/00 [58] Field of Search 335/186, 166, 167, 171,

335/164, 165, 160, 159; 340/52 E, 278; 180/82 C, 96; 307/114, 10 AT, 10 SB; ZOO/61.58 B; 123/179 R, 179 B [56] References Cited UNITED STATES PATENTS 2,361,564 10/1944 Platz 335/164 3,449,714 6/1969 Farley, Jr. 340/52 E Primary Examiner-Harold Broome Attorney, Agent, or Firm-John A. Haug: James P. McAndrews [57] ABSTRACT A manually set magnetic relay is utilized to override an electrical interlock in a one-time operation. Once the relay has been utilized, it automatically disables itself and must be manually set again for another operation. The relay includes an electromagnetic coil which closes a set of load contacts that are connected in parallel with the electrical interlock. A secondary circuit for energizing the coil includes'a pair of flexible conductors forming a switch which is latched open when the coil is de-energized. To close the switch and energize the coil, a manually actuated plunger engages one of the conductors and moves it from the latched position into contact with the other conductor of the switch. The plunger, during actuation, also holds the load contacts open to provide trip-free operation. A one-piece push button having flexible sidewalls is conveniently used to actuate the plunger.

9 Claims, 9 Drawing Figures PATENIEDFEB ,SHEET 10F 2 Jinnrn ll'fVA LOGIC MODULE STARTER /l4 SOLENOID PATENTEDFEB 41915 1864,5550

' SHEET 2 OF 2 v is w FIG.9

l MANUALLY SET MAGNETIC RELAY CROSS-REFERENCES TO RELATED APPLICATIONS This application relates to subject matter disclosed and claimed in copending application Ser. No. 421,889 entitled Manually Set Switching Devices, filed Dec. 5, 1973, and copending application Ser. No. 421,903 entitled Manually Set Magnetic Relay," filed Dec. 5, 1973, and copending application Ser. No. 421,904 entitled Push Button filed Dec. 5, 1973, all of the copending applications having the same assignee as the present application.

BACKGROUND OF THE INVENTION The present invention relates to the field of electrical relays and, more particularly, is related to a singlecycle magnetic relay which must be manually set before each operation.

It is well known to provide electrical interlocks in systerns to prevent operation unless specific conditions have been met. For example, as a safety measure in automobiles, the ignition system may be disabled until the driver and all of his passengers have fastened their seat belts. To implement such a system, an electrical interlock operated by sensors or swtiches sequentially set by the driver and passengers entering the car and fastening the belts may be provided in the ignition system of the automobile. Unless the belts are fastened after entry, the interlock disables the ignition system and the engine cannot be started.

It will be recognized that a failure of the electrical interlock system may completely disable the ignition sys tem and prevent operation of the automobile. Such a situation may not only be frustrating to the driver and his passengers but also could prove to be a serious hazard particularly in an emergency situation in which the automobile must be moved.

To remedy the situation and eliminate the possible hazards posed by the electrical interlock it has been suggested that an override relay be provided to bypass the electrical interlock. The relay must be manually set before each override operation and disabled after operation. Naturally, to prevent repeated use of the relay, it is located in a position not readily accessible to the driver except in an emergency situation, and one likely location for the relay is the engine compartment.

It is, accordingly, a general object of the present invention to disclose a manually set magnetic relay which automatically disables itself when de-energized to limit its use to single-cycle or one-time operations.

SUMMARY OF THE INVENTION The present invention resides in a manually set magnetic relay for one-time operations. The relay has particular utility as a device for overriding an electrical interlock since it must be manually set prior to each use and automatically disables itself after use.

The relay is comprised of first switch means operatively connectible in a load circuit such as the circuit controlled by the electrical interlock. Electromotive force generating means including an electromagnetic coil is operatively connected to the first switch means for completing the load circuit upon energization of the coil. Second switch means are serially coupled to the coil to permit energization and de-energization of the coil, for example, when the electrical interlock is to be bypassed. The second switch means includes first and second movable conductors positioned in overlying relationship for movement in and out of electrical contact. Latch means is operatively engagable with the first conductor of the second switch means for holding the first conductor in a latched position out of contact with the second conductor. Consequently, the coil of the electromotive force generating means cannot be actuated. The electromotive force generating means is also operatively coupled to the first conductor of the second switch means for moving the first conductor into the latched position. Hence, when the coil of the force generating means is de-energized, the first conductor remains held in the latched position and the relay becomes disabled, at least temporarily. To remove the relay from the disabled condition, manually operable actuator means engage the first conductor of the second switch means to move the first conductor out of the latched position. The first and second conductors are then placed in contact to ready the relay for another operation. Accordingly, the magnetic relay must be manually set prior to each override operation and automatically disables itself for subsequent operations until it is again manually set.

A push button suitable for use in operating the relay and similar devices when positioned within a protective cover is formed by a one-piece member having a flexible annular side wall circumscribing and integrally joined to a centrally located, relatively rigid displaceable depressing portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an electrical diagram illustrating one environment in which the manually set magnetic relay of the present invention may be employed.

FIG. 2 is a perspective view of the magnetic relay with the protective cover removed to expose the principal components.

FIG. 3 is a plan view of the relay as shown in FIG. 2 with the cover removed.

FIG. 4 is a side elevation view of the magnetic relay in FIG. 2 with the protective cover illustrated in section.

FIG. 5 is an end view of the magnetic relay with the protective cover illustrated in section.

FIG. 6 is a fragmentary view of the push button on the protective cover in section.

FIG. 7 is an enlarged fragmentary view showing the manually actuated plunger, the conductors of the secondary circuit in the open and latched positions and the load contacts in the open position.

FIG. 8 is a fragmentary sectional view similar to FIG. 7 showing the same components when the plunger is depressed.

FIG. 9 is another fragmentary sectional view similar to FIGS. 7 and 8 after the plunger is released from the depressed position illustrated in FIG. 8 and the relay is energized.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. I is an electrical diagram showing schematically the manually set magnetic relay of the present invention in the starting circuitry of an automobile having an electrical ignition interlock. The interlock normally prevents energization of the electrical starter motor unless the seat belts have been properly fastened in each of the occupied seats of the automobile. It should be understood, however, that the magnetic relay of the present invention can be employed in other environments to override an interlock or perform other functions to which its operation is suited.

The manually set magnetic relay of the present invention, generally designated 10, is connected serially in the electrical starting circuit between the ignition switch 12 and the starter solenoid 14 on the starter motor (not illustrated). The ignition switch 12 is, of course, connected to one of the battery terminals. the B terminal being illustrated, and the starter solenoid 14 would be connected to the other terminal, illustrated as the ground terminal, through the frame of the automobile. A starting switch 16 is also serially connected with the magnetic relay between the ignition switch 12 and the solenoid 14. The ignition switch 12 and the starting switch 16 are generally incorporated in a single switching device manually operated by means of the ignition key and are closed sequentially, the switch 12 being closed first and the switch 16 being closed second by rotating the ignition key through several index positions, the last of which closes the switch 16 to energize the starter solenoid 14 and turn the starter motor. Usually the last index position is springbiased so that the starting switch 16 opens upon release of the key. The ignition switch 12 also energizes other portions of the electrical system such as the spark coil, fuel pumps and instrumentation needed during operation of the engine.

The seat belt interlock system includes a logic module l8 and an interlock relay 20. The logic module 18 receives signals from sensing switches indicating which seats of the automobile are occupied and which seat belts have been fastened. If the seats are first occupied and then the respective seat belts are fastened in that order, a go" signal normally issues from'the module 18 to actuate the coil of the interlock relay 20 and close the relay contacts. The relay contacts in the closed position complete the starting circuit through the switches 12 and 16 to the starter solenoid l4 and permit the starter motor to be engaged. if the logic module detects an unfastened seat belt in one of the occupied seats, or if the sensing switches are not actuated in the proper order, indicating, for example, a permanently buckled seat belt, the interlock relay 20 is not energized and the starting circuit remains'open. Also, however, if the logic module 18 is faulty and inoperative, the interlock contacts may not close and starting the automobile cannot take place in its intended fashion.

The manually set magnetic relay is employed in parallel with the interlock relay to override the interlock when it is inoperative for any reason and therefore permits the automobile to be started. The magnetic relay 10 is comprised of electrical components including an electromagnetic relay coil 22, a load switch 24 operated by the coil and a latching switch 26 in a secondary circuit with the coil. The contacts of the load switch 24 are connected in parallel with the contacts of the interlock relay 20 so that they may duplicate or override the relay 20 when the interlock system fails. In order to close the load switch 24, however, the latching switch 26 must be closed and the magnetic coil 22 must be energized through the ignition switch 12. The latching switch 26, as described in greater detail below, must be manually set to the closed position and is automatically opened to disable the relay 10 when the coil 22 is de-energi zed after the ignition switch 12 is opened to shut off the automobile engine. Hence, the magnetic relay 10 provides a single-cycle override or bypass operation of the seat belt interlock system for each operation of the automobile engine. It will be understood that the manually set magnetic relay 10 would be located in a position not readily accessible to the driver of the automobile, for example in the engine compartment, so that the seat belt interlock system is not routinely overridden.

.FIG. 2 illustrates a construction and the principal components of the manually set magnetic relay 10. The principal components of the relay including the coil 22, the load switch 24 and the latching switch 26 are all supported on a base plate 30 formed preferably from an insulating material such as a plastic or fiberboard. The electromagnetic coil 22 includes a ferromagnetic support bracket 32 which is fixedly attached to an elevated platform 34 at one end of the base plate. One lead 36 from the coil is attached to a terminal 38 having a connecting pin 40. The other lead 42 is connected to a terminal 44 on the plate 30.

The coil 22 is supported by the bracket 32 in spaced relationship above a clapper 50 attached to a resilient and conductive clapper arm or spring 52. The one end of the clapper arm 52 is clamped to the base plate 30 along with the bracket 32 and the coil. The same end of the arm connects with the electrical load terminal 56 and its associated connecting pin 58.

The opposite end of the clapper arm 52 extends in cantilever fashion from the platform 30 on which both the arm and the relay coil 22 are mounted. A load contact 52 is positioned on the end of the arm 52 directly below a stationary and mating load contact 64 held by the contact support 66. The contact support 66 is fixedly mounted on the base plate 30 as shown and .is electrically connected with the load terminal 68 which may also be provided with a connecting pin (not shown) similar to pins 40 and 58.

it will be understood that when the relay coil 22 is energized, the clapper 50 is pulled upwardly by the electromagnetically generated force of the coil and, correspondingly, pulls the clapper arm 52 and contact 62 upwardly into engagement with the stationary contact 64. When the relay coil 22 is deenergized, the clapper 50 and arm 52 drop downwardly to the position illustrated in which the contacts 62 and 64 are open.

The latching switch 26 is formed by two resiliently flexible wires or conductors 70 and 72 which are positioned in an angularly disposed and overlying relationship when in contact. The conductor 70 is attached to the base plate 30 at a terminal 74 having a connecting pin 76 and extends from the terminal 74 in a direction generally parallel to the resilient clapper arm 52 to a ,latch 80 illustrated more clearly in FIGS. 3-5. Being resilient, the conductor 70, can be flexed in directions generally perpendicular to its axis so that one end of the conductor can be lifted onto the latch 80 as illustrated in FIGS. 2-5 or moved off of the latch as shown, for example, in Fl GS. 8 or 9. The conductor in the unflexed condition would assume a position intersecting the latch 80. Consequently, when the conductor is in the latched position, it is resiliently biased downward or toward the base plate 30 and when it is moved out of the latched position to a station at one side of the latch as illustrated in FIG. 8, it is biased generally against the side of the latch 80.

The conductor 72 is mounted to the base plate 30 at the terminal 44 and extends in cantilever fashion from the terminal transversely across the clapper arm 52 and under and slightly beyond the conductor 70 in a direction generally perpendicular to the conductor 70. An insulating pad 84 is fixed to the clapper arm 52 and interposed between the conductor 72 and the arm to provide a mechanical coupling and electrical isolation.

The flexible conductor 72 rests at all times on the insulating pad 84. It will be readily understood, therefore, that as the coil 22 is energized and de-energized to raise and lower the clapper arm 52, the cantilevered or free end of the conductor 72 will flex up and down with the clapper arm. The position to which the conductor 72 is lowered by the clapper arm 52 and the height of the latch 80 above the support surface of the base plate 30 are selected so that the conductors 70 and 72 are out of contact when the conductor 70 is in the latched position and the coil 22 is de-energized. When the coil 22 is energized and the clapper arm 52 is pulled upwardly with the conductor 72, the conductors 70 and 72 remain in contact with the conductor 70 is elevated slightly above the latch 80 as illustrated in FIG. 9..

The magnetic relay is manually set for operation by means of an actuator comprised primarily of a slide or plunger 90 which is supported for sliding movement toward and away from the base plate 30 by means of two upright guides 92 and 94 fixedly attached or integrally formed with the base plate. The latch 80 forms an integral portion of the lower end of the guide 92. The plunger 90 takes the form of a flat board and is composed of an insulating material such as a fiber board. The edges of the plunger are received in sliding relationship in grooves of the upright guides. The upper end of the plunger includes a knob 96 which is captured in the aperture of a return spring 98 taking the form of a leaf spring spanning the tops of the two guides 92 and 94. A lower corner of the plunger 90 includes a cut-out adjacent the latch 80 and generally registering with the conductor 70 for reasons to be described in a greater detail below.

The components of the magnetic relay 10 mounted on the base plate 30 are preferably enclosed within a protective cover 100 illustrated in FIGS. 4-6. The cover mates with or rests upon and is attached to the base plate 30 and may be sealed with the plate by means of a gasket or other sealing material interposed between the cover and the plate.

To manually actuate the plunger 90 when the cover 100 is in place, a one-piece elastomeric push button 102 is mounted on the top of the cover and projects through an aperture 104 in the cover into contact with the knob 96 at the top of the plunger 90. The push button 102 as illustrated most clearly in FIG. 6 has a generally hat-shaped configuration with a flexible, annular side wall 106 circumscribing a centrally located and relatively rigid displaceable depressing portion 108. The side wall and the central depressing portion are generally cylindrical in shape and are co-axially positioned relative to one another with the side wall located externally of the depressing portion and integrally connected to the one axial end of the depressing portion located outside of the cover 100. A mounting flange 110 is integrally connected to the side wall 106 at the axial end opposite the connection of the side wall and the depressing portion for mounting the push button 102 between the cover 100 and a clamping plate 112 riveted to the cover and having an aperture 114 through which the push button extends. The flange 110 includes a bead 116 on its peripheral edge to insure that a dustproof and fluid-tight seal is generated with the cover 100 when the flange is sandwiched between the cover and the clamping plate 112.

When the push button 102 is operated by depressing the upper end of the button illustrated in FIG. 6, the rigid portion 108 is displaced downwardly through the apertures 104 and 114 and the thin side wall 106 merely flexes outwardly. Since the portion 108 is relatively rigid and is in contact with the knob 96 at the top of theplunger, displacement of the portion 108 produces a corresponding downward displacement of the plunger 90. When the push button 102 is released, the flexible side walls 106 return the depressing portion 108 to the illustrated position and the return spring 98 lifts the plunger 90 away from the base plate 30 regardless of the orientation of the relay when it is mounted to other structure.

If desired knob 96 may be fixedly attached to the push button 102 as by providing an aperture in the bottom surface of the button and forcing knob 96 into a driving fit with the aperture, or by using adhesive or any other conventional means. When so attached the natural resiliency of the button member may be used to supplement or even replace the return spring 98.

OPERATION While the overall operation of an exemplary system incorporating the manually set magnetic relay 10 is described above in conjunction with FIG. 1, the internal operation of the relay is explained below primarily in conjunction with FIGS. 7-9.

Prior to being set for a single-cycle operation, the magnetic relay 10 is in a disabled and normally open condition with the load switch 24 formed by contacts 62 and 64 open and the latching system 26 formed by conductors and 72 also open as illustrated in FIG. 7. The plunger 90 is held in the elevated position illustrated by the return spring 98 shown in FIG. 2. It will be understood that in the disabled condition, the load contacts 62 and 64 will not be closed if power is applied to the relay because the latching switch 26 is open with the conductor 70 of the switch 26 resting in the latched position out of contact with the conductor 72.

To set the relay for operation, the plunger 90 is displaced downwardly by manually pressing the push button 102 in FIG. 5. The plunger cut-out registering with the conductor 70 includes a camming surface 120 which engages the conductor 70 as the plunger is displaced and moves the conductor laterally off of the latch to permit the conductor to snap downwardly in contact with the conductor 72 extending transversally thereunder as shown in FIG. 8. Thus, the switch 26 formed by the conductors is closed and the coil 22 may be energized.

It will also be noted in FIG. 8 that when the plunger is depressed, the lower edge 122 of the plunger engages the clapper arm 52 and presses it downwardly against the base plate 30 to hold the load contacts 60 and 62 open for trip-free operation. Holding the load contacts open when the plunger is depressed prevents the relay 10 from being used to permanently defeat the electrical interlock system and the single-cycle feature of the relay. For example. if the push button 102 or plunger 90 is purposely jammed or fixed in the depressed position to hold the latching system 26 closed, the relay will not permanently override the electrical interlock because the load contacts 60 and 62 are locked open at the same time.

When the plunger 90 is released, the return spring 98 lifts the plunger out of engagement with the conductor 70 and the clapper arm 52. In this event, the arm 52 returns to the unflexed position illustrated in FIG. 7 with the load contacts open while the conductors 70 and 72 assume the phantom position illustrated in FIG. 9. The conductors in the phantom position are in contact with one another since the conductor 70 is biased slightly downward as well as laterally into engagement with the latch 80.

When power is applied to the relay in the set condition, the coil 22 is energized through latching switch 26 and pulls the clapper arm 52 upwardly to close the load contacts 62 and 64, complete the load circuit to the starter solenoid 14 shown in FIG. 1 and thusly by-pass the interlock relay 20. At the same time the conductor 72 is elevated by the clapper arm 52 and in turn elevates the overlying conductor 70 to a position above the latch 80 illustrated in FIG. 9. As the conductor 70 is moved upwardly, the lateral biasing force causes it to slide over the conductor 72 and the latch 80 against the guide 92.

The clapper 52 and the conductors 70 and 72 remain in the elevated position of FIG. 9 as long as the coil 22 is energized. For example, in FIG. I, as long as the ignition switch 12 remains closed, the starter solenoid 14 can be engaged and reengaged to start the engine, and if the engine subsequently stalls, it can be restarted without resetting the relay 10.

When the coil 22 is de-energized, for example, by opening the ignition switch 12 in FIG. 1, the clapper arm52 and conductor 72 spring downwardly to the positions illustrated in FIG. 7 and at the same time the conductor 70 drops into the latched position also indicated in FIG. 7. Thus, the load and latching switches 24 and 26 open and the relay is returned to its disabled condition in which the electrical interlock may resume its normal function.

It will thus be seen that a magnetic relay has been disclosed which must be manually set for a one-time operation and which automatically assumes a disabled condition following a single energization and deenergization cycle. The relay has particular utility as an override device for an electrical interlock and provides trip-free and single-cycle operation to prevent the interlock from being permanently defeated.

While the relay has been described in a preferred embodiment, it should be understood that numerous modifications and substitutions can be had to the specific structure disclosed without departing from the spirit of the invention. For example, it should be readily apparent that the push button 102 can be varied in style and form or may be eliminated altogether if a sealed enclosure is not essential. The precise shape of the plunger 90 with the camming surface 120 and the mounting of the plunger on the base plate 30 may be varied as long as the plunger serves the function of moving the conductor 72. Furthermore, the construction of the plunger bringing it into engagement with the clapper arm 52 to provide a trip-free operation of the relay is not essential but is a desirable feature in a relay of this type. Accordingly, the present invention has been described in a preferred embodiment by way of illustration rather than limitation.

I claim:

l. A manually set magnetic relay for one-time operations comprising:

first switch means operatively connectible in a load circuit;

electromotive force generating means including an electromagnetic coil operatively connected to the first switch means for completing the load circuit upon energization of the coil;

second switch means serially coupled to the coil to permit energization and de-energization of the coil, the second switch means including first and second movable conductors positioned with portions of the conductors in overlying relationship for movement in and out of electrical contact to close or open the circuit through the second switching means and the coil;

latch means operatively engageable with the first conductor of the second switch means for holding the first conductor in a latched position out of contact with the second conductor of the second switch means; the electromotive force generating means also being operatively coupled to the second conductor of the second switch means for moving the first conductor into the latched position; and manually operable actuator means engagable with the first conductor of the second switch means for moving the first conductor out of the latched position. 2. A manually set magnetic relay as defined in claim I wherein:

the first and second conductors of the second switch means are flexible conductors resiliently biased into contact in the unlatched position of the first conductor and positioned in angularly disposed and overlying relationship when in contact. 3. A manually set magnetic relay as defined in claim 2 wherein:

the electromotive force generating means is mechanically coupled by the second conductor of the second switch means to the first conductor of the second switch means for latching whereby energization of the force generating means moves the first conductor in contact with the second conductor toward the latched condition by means of the second conductor and de-energization of the force generating means leaves the first conductor in the latched position out of contact with the second conductor. I 4. A manually set magnetic relay as defined in claim 3 wherein: I I

the first switch means includes a clapper arm operatively connected with the coil of the force generating means for closing the first switch means and a switch contact mounted on the clapper arm; and the second conductor of the second switch means is operatively engaged with the clapper arm for movement of the first conductor with the clapper arm in response to the force generating means. 5. A manually set magnetic relay as defined in claim I wherein: v

the latch means includes a support member on which the first conductor of the second switch means rests in the'latched position out of contact with the second conductor; and

the manually operable actuator means comprises a manually displaceable member engagable with the first conductor in the latched position to force the first conductor from the support member 6. A manually set relay as defined in claim wherein:

the manually displaceable member of the actuator means is a plunger having a camming surface engaging the first conductor of the second switch means to move the conductor from the latched position.

7. The manually set magnetic relay of claim 6 wherein the manually operable actuator means further includes a return spring connected with the plunger for moving the camming surface of the plunger away from the second conductor in the latched position.

8. A manually set relay as defined in claim 1 wherein:

the manually operable actuator means is also engagable with the first switch means for positively holding the first switch means open before moving the first conductor of the second switch means out of the latched position.

9. The manually set magnetic relay ofclaim 1 further including:

a cover enclosing the first and second switch means. the electromotive force generating means and the latch means; and wherein:

the manually operable actuator includes a push button projecting through the cover and comprised of a resilient one-piece hat-shaped member mounted in sealing relationship to the cover. 

1. A manually set magnetic relay for one-time operations comprising: first switch means operatively connectible in a load circuit; electromotive force generating means including an electromagnetic coil operatively connected to the first switch means for completing the load circuit upon energization of the coil; second switch means serially coupled to the coil to permit energization and de-energization of the coil, the second switch means including first and second movable conductors positioned with portions of the conductors in overlying relationship for movement in and out of electrical contact to close or open the circuit through the second switching means and the coil; latch means operatively engageable with the first conductor of the second switch means for holding the first conductor in a latched position out of contact with the second conductor of the second switch means; the electromotive force generating means also being operatively coupled to the second conductor of the second switch means for moving the first conductor into the latched position; and manually operable actuator means engagable with the first conductor of the second switch means for moving the first conductor out of the latched position.
 2. A manually set magnetic relay as defined in claim 1 wherein: the first and second conductors of the second switch means are flexible conductors resiliently biased into contact in the unlatched position of the first conductor and positioned in angularly disposed and overlying relationship when in contact.
 3. A manually set magnetic relay as defined in claim 2 wherein: the electromotive force generating means is mechanically coupled by the second conductor of the second switch means to the first conductor of the second switch means for latching whereby energization of the force generating means moves the first conductor in contact with the second conductor toward the latched condition by means of the second conductor and de-energization of the force generating means leaves the first conductor in the latched position out of contact with the second conductor.
 4. A manually set magnetic relay as defined in claim 3 wherein: the first switch means includes a clapper arm operatively connected with the coil of the force generating means for closing the first switch means and a switch contact mounted on the clapper arm; and the second conductor of the second switch means is opeRatively engaged with the clapper arm for movement of the first conductor with the clapper arm in response to the force generating means.
 5. A manually set magnetic relay as defined in claim 1 wherein: the latch means includes a support member on which the first conductor of the second switch means rests in the latched position out of contact with the second conductor; and the manually operable actuator means comprises a manually displaceable member engagable with the first conductor in the latched position to force the first conductor from the support member.
 6. A manually set relay as defined in claim 5 wherein: the manually displaceable member of the actuator means is a plunger having a camming surface engaging the first conductor of the second switch means to move the conductor from the latched position.
 7. The manually set magnetic relay of claim 6 wherein the manually operable actuator means further includes a return spring connected with the plunger for moving the camming surface of the plunger away from the second conductor in the latched position.
 8. A manually set relay as defined in claim 1 wherein: the manually operable actuator means is also engagable with the first switch means for positively holding the first switch means open before moving the first conductor of the second switch means out of the latched position.
 9. The manually set magnetic relay of claim 1 further including: a cover enclosing the first and second switch means, the electromotive force generating means and the latch means; and wherein: the manually operable actuator includes a push button projecting through the cover and comprised of a resilient one-piece hat-shaped member mounted in sealing relationship to the cover. 